Remote-control and supervision system



United States Patent fi 2,694,802 Patented Nov. 16, 1954 Fice Claims priority; application GreatiBritain T Februaryr26 l95l I 5 Claims. (Cl:- 340--163) Thisiinvention ..relates to -calhpriority: equipment in party line remote control and.-=supe11visor-y systems.

Hitherto,- call: priority equipment: for=party I lineiremote controland.supervisorysystemshas :madeuseof a system of. calling impulsesnof.dilferentidurations permanently allotted-to thelvarious-stations .using the, party line; the station allotted the longestcallingimpulse securingprionz ity.where severalstations commence to call simultaneous'l-y-.- The practical .diflicultyof time discrimination set a limit to the; number of. stations which can. :be catered :for by systems of this kind. and epreventthe use et -certain; forms of signalling in such systems and a principahobjec'tof the; present invention-is to provide. av call priorityarrangement. which is notnboundsby these-. limitations.--

Accordingdo .thetinvention there is provided-in a party: line remote control or supervisory: system, callizprior-ity equipment comprising a: number of stat-ions iandt-compris-f ingmeans for. securing :that Whenanytwo or more-stations call simultaneously the station nearest to a predetermined endof the systems obtains prior ityiover the other-calling stations.

According -.t ot the :inventiontthere ris .-further-.provided in a party linerremote control =ortsupervisory-system, cal-l; priority equipment: comprising! a communication .circuitn having agfirstl transmissionpathianda secondrtransmissiona path,. a. first. end-.stationconnected to :boththe i said transa missionpaths at one end of the said circuit; asecond-end. station connected to bothitransmissionrpathsatatheiothern end of thesaid circuit at least oneintennediatestation con'-.- nected, or each connectedif more thancne; to-bothtransmission pathsat anaintermediatespoint ori-"points in the said circuit, at thedntermediate station or at each of them'. it morethanone a. sender,- azreceiver; a connection .-be-i'- tweenathe receiver and r each of the :"transmis'sion paths, a," connection betweemthe sender andithe firsttransmissionc path at a point nearen the first endistationt-han tthe pointn of connection between the receiver-and-the4first-trans-- mission path,- a connection I-ron'n-thesenderto the second transmission path at ."a' point nearerto the second -'end=station: than sthet pointaof =connection of the receiver to thesecond. transmission: path, meansnfor interrupting each: of the. .transmissionrpathsat a. point between the .points of 1 connection thereto of the sender and receiver, meansafor interruptingthe connection between thereceive'r and the first transmission path, meansunder control of theisender. to operate the said three interrupting means, at eachend station a sender; and areceiven'at the first end station a connectionfrom" the receiver to ithe firstdmnsm'ission path and means under control .ofthe'isenderfot inter ruptingtthat connection'anda connection frotnthe .sen'd'er" to the :second transmission path; at thesecond end statiozf a connection fromuhe sender to the firshtransmissiofi path and from the receiver'to the second transmission path and at each station; beit an'end station 'or a'n inter mediate station, means in the senderfor'sending a calling signal to the transmission-"path or 'paths to which such sender'is connected, a connection between the receiverand 1 the sender andmeans in the receiver responsive to a calling signal receivedoverone of the transmission paths for disabling the sender, whereby stations whose senders are idle when. anotherstationis sending a calling'signal, receive such callingsignal to disable their'rsenders'randr wherebywhen the senders? at two or'more'stations' simuh" taneouslyzsendra callingsignal, the station'ozt'suchtwofl or more stations. :WhichLis nearest, along =thellength. of the-l said Icommunicat-ion circuits to. the first end station; :orwthe... first: end ."station. itselfi .if it is one :of SllChIntWO"OI-'I1'1OI"6 11 stations; is unable to .receivera calling isignal.firornx'either. transmission pathxandi all. other stations. receive av calling senders.a;:

signal over the second transmission paths to disabletheir:

The invention will be more readily IIIldEISiOOdfl'IOIIIIthfii followingcdescription. l of .an' embodiment thereoftillustrated: in. theraccompanyingadrawingsfin which:

Fig; '1 is .a .blockrischematieiof theiembodiment', rand F 1g." 2 is: a more detailed "circuit diagram: of theIembodiv ment:

The embodimenthas' been'designed to meet arequirea. mentefor callspriorityz equipment. in remote J supervision '1.

and/or. control xofvia plurality' of lsubstations. from': one

or more main station's; onra: four wvire party lines Fig. 1' showsthe'xbasictlayout of call-priority equipment: on a partyi linerzwith two. endfstations tandxa numberi'of 'i intermediate stationsiof which threeare shown. It is nec-.. essary' to ensurezthato'nly one station at a. time'obtains use.oftherparty line; iandiFig'uref l shows a method of achieving this;

A four-wire party line havingrone. conductive line pair.

1, shown by a singl'e'lineiandanother conductive lineipair 2,- also shown 'by a single line; runsi. thelwhole length be-i' t\veen*:theitwo rend stations, one shown-as being .at the north of the ilineythei other tat "the'isoutht- The rintermediate stations are trapped on to thepartydine E at intermediate positions:

The :end stations andiintermediate: stations 1 each. have a transmitteriandl'ai receiver :and,uexcept:in the 'case of the:

end stations each receivertand'each' transmitter hasa con-r.

nection' to 'eachro'f 'thedtwo-Wire line'sof the .party lines a:

One two-wire line' 1.. is intended? for: north going trans mission; and the otherilineinfor s'outhagoing transmission;

Each two-wire line can be interrupted at each inter-;-.;

mediate station ubetwe'en -the -ipoints of connection: from the receiver and the isender of that. station-'1 The iconnec'az tion from line 1 to the receiver at eachzstation is also;-

capable of beingainterruptedgrall4these: interruptions; being under =control of the senderiat the station; wvThe operation of the system can be readily understood from the::following examplezn Assume that the N01 2 intermediate station wishes to send. 'Upomstartlof the -sender ZISQreIayIiZA operatesi Operation of 'reIay' -ZAL causeszbreak.contacts 201., 2a2 fand-2a3 to openline 1, the connection 2C1 to receiver" to 2IS; and line 2--respect-ively. Since contaetZal is open;

sen'der2lS-l can send only northward along line i. and only southwards along :line 2; contact-2:13 being also open andopen circuitin'glinefl northwards of the intermediate'.

stationNO-xZ. The 'rece'iver at each stationis arranged to' disable the sende'r the'reat wh'en signals are: being re-:

ceivedso that' stations north of the N0 2 intermediate station receive-signalstherefrom; over line 1, the :connecw tion therefrom to the receiverbe1ngmadevia their'closedf a2 relay contacts. Stations to the south of N0." 2.inter-" mediate station" receive 'signals' therefrom over line 2 via the"connection=therefrom to=their receivers. Intermediatei station-Nob 2 .thus 'looksaout allkotherstations, in both directions; from 'sending whilst it is sending by 'meansof the disabling" c onnections=-3 which-'extends from each receiverto its assoeiatedsender in 'these other stationsw if twostations commenceto sendat the same time; they both operate'thei'rA relay'and'the more northerly of the two stations cuts 'off' it's receiver'from'iline 11 at its openaZcontacts-andcannot receive'signals from the station to the south- I The more southerly. station however receives thes'ignalsxof the-more-n-ortherly. sending. stationalong line 2 and the sender at the more southerly stationis dis-.

abled, giving priority "to the .morehnortherly 1 station;

The same applies-wwhere more than Itwo r stations-startto send'isimultaneously; the northern most station .securing the line.

For thispurpos'e theend stations are on the samefooting as the interm'ediate= stationsa- The end stations have substantially the same line access as intermediate stations '"but'as they'areat the ends-"of the lineg'someof theapparatns s'hown in the intermediate sta-. tions can beomittedT There. is no need for the al and'a3;

contacts for instance at the end stations as the line only goes in one direction from each of the end stations.

The south end station receiver has no need for the connection to line 1 as there is no possibility of northgoing signals coming to it and once it has commenced to send and has seized the party line, it has blocked all stations north of it owing to receipt of its signals by the receivers at those stations which receivers, in turn, block the associated senders at those stations.

The A relay can thus be omitted altogether at the south end station.

At the north end station a relay NA is provided having a pair of a2 contacts which are retained to preserve the priority of this station as the most northerly, in case this station starts to send simultaneously with another station.

In the embodiment described, the end stations are associated with the two main stations of the remote control and supervisory system whose role in the system is to receive supervisory indications from and send control signals to substations of the system with which the intermediate stations are associated. If supervisory functions only are required, the end stations could have the senders omitted and the connection to the receiver at the north end station would then be direct and not through the m2 contacts associated with relay NA, which relay is controlled by the sender at this station similarly to the control of the A relays at the intermediate station.

The main station or stations could equally well be associated with one or more of the intermediate stations as the difference between end stations and intermediate stations arises from their positions along the party line and not from the functions of their associated stations in the remote control and supervisory system.

Intermediate stations without senders could also be connected to the party line and they would not need to have any a contacts breaking the party lines or the receiver connection. The receivers at such listening stations would need connections to both party lines however to enable them to receive signals from stations on both sides.

The detailed circuits will now be described in relation to Fig. 2 which shows the two end stations and two intermediate stations.

All the intermediate stations are similarly equipped; No.

1 intermediate station for instance has a sender 4 and a receiver 5.

In each sender there is a contact K which represents the sending mechanism and may be a hand-operated key or other switch device according to the requirements of the remote control or supervisory system in which the invention is incorporated. Operation of contact 2K in the sender 8 of the No. 2 intermediate station connects a battery 2S6 across the twin conductors of both party lines over back contacts 2d1, 2d2 of a relay 2D in receiver 7. Operation of contact 2K also operates relay 2A in sender 8 which, at contacts 2:11, 2a2, breaks the conductors of line 1 representing the No. 1 party line; at contacts 2a3, 2a4, similarly breaks the conductors of line 2 representing the No. 2 party line, and at contacts 2115, 2116 breaks the connections from the conductors of line 1 of the No. 1 party line to receiver 7.

Relay 2A is slow to release so that it will remain operated during repeated openings and closings of the 2K contact in the course of signalling. Assuming that the No. 1 intermediate station has seized the line, the receivers of other stations will receive battery potential from the battery 156 at the No. 1 intermediate station, over the connections from one or other of the party lines to the terminals of their receivers; the more northerly stations receiving the potential over line 1 and the more southerly stations receiving the potential over line 2.

To explain the effect of this application of potential from the battery 156 at the No. 1 intermediate station, the response at the No. 2 intermediate station will now be considered.

The receiver 7 at the No. 2 intermediate station like the receivers at all the other stations, has two relays, 2D and 2R. Both these relays operate to battery 186 via the circuit 1K, back contacts idl, 1d2, at the No. 1 intermediate station, the twin conductors of line 2 to relay 2D and 2R in parallel at the receiver 7 in the No. 2 intermediate station.

At the intermediate station No. 2, when relay 2D operates its contacts 2d1 and 2d2 open and break the connections from the sender 8 to the party lines 1 and 2 and open the operating circuit of relay 2A at contact M1.

Relay 2D is slow to release and holds up, in the event of intermittent pulsing of contact 1k at the No. 1 intermediate station, thereby to hold other stations locked out from sending. Relay 2;- on the other hand, opens and closes with the repeated operations of contact 1K and its contacts 2r open and close the circuit from battery 9 to outgoing terminals T1, T2, which lead to signal responsive apparatus (not shown) the form of which is dictated by the control or supervisory requirements of the system in which the invention is incorporated and which forms no part of the invention.

The receivers at other stations operate in the same way as described with respect to the No. 2 intermediate stations, except that stations to the north of the sending station receive the signals over the party line 1 since the north-going circuit on the line 2 is broken by the opened a3, a4 contacts of the sending station. Similarly, the south-going circuit on the line 1 is broken at the opened a1, a2, contacts of the sending station.

The operations at the south end station, when receiving, differ from those at other stations in that there is no A relay to be disconnected.

Any station which is intended for listening only and therefore having no sender, has its receiver connected to the party line conductors in the same way as shown in Fig. 2 but without the insertion of any a5, a6 contacts in the connections where shown in Fig. 2. The A relay and its contacts are also omitted, and there is no need to provide any means for interrupting the party lines.

In the event of two stations attempting to call simultaneously, the most northerly of these stations operates its A relay and disconnects its receiver at its a5, 116 contacts, from line 1 and breaks the circuit of line 2 at its opened a3, a4 contacts so that it cannot receive from the south along line 2. More southerly stations also cut off their senders from northward communication along line 2 at their opened a3, a4, contacts which is a double safeguard against reception of their calls by the northernmost station along line 2.

Stations to the south attempting to call at the same time do not disconnect their receiver from line 2 nor does the northernmost sending station break this path, and so these more southerly stations operate their D relays and disconnect their senders and (except in the case of the south end station) their A relays. As line 2 is interrupted by all sending stations simultaneously, at their (13, a4 contacts where more than two stations are attempting to send simultaneously, there will be a race between operation of their D relays and a station removed by one or more stations from the most northerly of those simultaneously sending may have its D relay operated by the signals of the station immediately to the north of it, or, if that D relay of the latter station operates first, by the signals of some still more northerly station, over the a3, a4 contacts, now closed, of the immediately adjoining northerly station. Whichever happens, however, the ultimate result is the same.

While the principles of the invention have been described above in connection with specific embodiments and particular modifications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of the invention.

What we claim is:

1. In a party line remote control or supervisory system, call priority apparatus comprising a first and a second communication path, a first and a second end station, a plurality of stations intermediate said end stations, each of said stations comprising receiving means and sending means associated therewith, the sending means associated with said first end station normally coupled to said first path, the sending means associated with said second end station normally coupled to said second path, the receiving means associated with said first end station normally coupled to said second path, the receiving means associated with said second end station normally coupled to said first path, the receiving means and sending means at each of said intermediate stations normally coupled to each of said paths in the directions of each of said end stations, separate disconnecting means at each of said intermediate stations for opening both said paths, for disconnecting the receiving means associated with said station from said first path in the direction of said first end station, and for disconnecting the sending means associated with said station from said second path in the direction of said second end station, each of said disconnecting means under control of the sending means associated with said station, additional disconnecting means associated with said second end station for disconnecting the receiving means thereat from said first path, said additional means under control of said sending means thereat, and separate disabling means at each station for disabling the sending means thereat, said disabling means under COntrol of the receiving means thereat, whereby upon simultaneous sending from at least two of said stations, the station nearest said second end station obtains priority over said other sending station to the exclusion of said farthest station.

2. Call priority apparatus as claimed in claim 1, wherein said sending means comprises a contact and a source of potential, said intermediate stations having said contacts and sources adapted to be normally coupled in seriesparallel relation with both said paths upon closure of the contact associated with said station, said first end station having its contact and source adapted to be normally coupled in series with said first path, said second end station having its contact and source adapted to be normally coupled in series with said second path.

3. Call priority apparatus as claimed in claim 2, where in said receiving means comprises a relay responsive to the application of potential from the source associated with any other of said stations whose contact is closed.

4. Call priority apparatus as claimed in claim 2, Wherein said disabling means comprises a disabling relay responsive to the application of potential from the source 1'3 associated with any other of said stations whose contact is closed, said disconnecting relay having contacts serially connected between said key, said source and at least one of said paths, said disabling relay being of the delayed release type.

5. Call priority apparatus as claimed in claim 2, wherein said disconnecting means comprises a disconnecting relay having three pairs of back contacts, a first pair of said contacts serially connected between said first path, a second pair of said contacts serially connected between said second path, said third pair of contacts connected in parallel to both said paths, said disconnecting relay being of the delayed release type.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,342,635 Lewis June 8, 1920' 1,562,210 Field Nov. 17, 1925 1,613,944 Field Jan. 11, 1927 1,863,089 Field June 14, 1932 1,950,108 Harrington Mar. 6, 1934 2,045,713 Judge June 30, 1936 2,047,631 Hershey et a1. July 14, 1936 2,126,209 Preston Aug. 9, 1938 2,174,291 Powell Sept. 26, 1939 2,183,245 Muehter Dec. 12, 1939 2,390,222 Muehter Dec. 4, 1945 

